Propeller



Feb. 17, 1931. I SHERER 1,793,339

' PROPELLER Filed Dec. 11, 1929 Patented Feb. 17, 1931 UNITED STATES PATENT OFFICE FRANK G. SEER-ER. OF LOS ANGELES, CALIFORNIA; ERNEST BROGMUS, OF CHICAGO. ILLINOIS, ADMINISTRATOR OF SAID FRANK G. SHERER, DECEASED, ASSIGNOR TO ROBERTS BROTHERS, OF CHICAGO, ILLINOIS, A COPAR'I'NERSHIP CONSISTING OF J. A. ROBERTS, J. H. ROBERTS, G. W. ROBERTS, AND W. E. ROBERTS PROPELLER Application filed December 11, 1929. Serial No. 413,151.

'rapid rotation of the blades in the air tends to produce a rarefaction of the air in the zone of rotation of the propeller and thus to reduce its propulsive efi'ect. This rarefaction is due in part to the tendency of the air to slip outwardly along the faces of the blades and oif their tips, under the influence of the centrifugal action set up by the propeller in its rapid rotation, and in part to the tendency of a vacuum to be formed along the trailing ed es of the blades.

t is the general object-of my invention to provide meansfor overcoming or lessening these objections, whereby greater efiiciency of the propeller and power plant as a whole is secured, and to do this in'asimple and practical manner.

In carrying out my invention I provide transverse fins or vanes on the driving face of the blades to reduce or prevent slippage of the air therealong. Adjacent these fins or vanes are openings in-the face of the blade leading to the interior thereof, and from the latter are other openings to the trailing edges of the blades- The air from the face of the blade entering the interior of the blade escapes through the trailing edge openings and prevents or reduces the vacuum or rarefac tion therealong. The vanesprevent or reduce rarefaction from this cause and increase the flow of air through the openings to the interior of the blade and out the trailing edge. I may also utilize the impulse reaction of the air on its way to the trailing edges of the blades to impart to the blades a forward thrust in the direction of their rotation.

Referring to the accompanying drawings, which illustrate, by way of example, two embodiments of my invention,-

Fig. 1 is a face view of the propeller looking in the direction of the axis of'revolution and at the driving or thrust faces of the blades; r

Fig. 2 is a view at right angles to Fig. 1;

Fig. 3 is a longitudinal section on the line of Fig. 1, showing on an enlarged scale the interior construction of the blade;

Fig. l is a cross-section of the blade on the line ll of Fig. 1 looking in the direction of the arrows; and

Fig. 5 is a similar face view of a portion of ablade showing another location adjacent the vanes of the openings in the face of the blade.

The propeller shown in these drawings is of the hollow-blade type made of metal or other suitable material and of the usual or desired form. contour and construction. On the driving faces of the blades 10 are transverse ribs. vanes or fins 11 projecting outwardly therefrom sufliciently to retard or prevent the slippage of the air outwardly along said faces and toward the tips of the b ades under the influence of the centrifugal action due to the rapid rotation of the propeller.

These fins are also preferably of metal and of stream line formation, as shown. and preferably extend across the interior hollow section of the blade. as shown at 11a in Fig. 3, to divide the mterior of the blade into compartments. In this way they also strengthen the construction of the blade. The fins may be secured in position in any desired manner, as by welding or otherwise. These fins are slightly curved, as indicated. the center of their curvature being slightly eccentric.

to the axis of the propeller.

In the driving faces of the blades are formed slots or openings 12 leading to the interior thereof. These slots are preferably close to the inner faces of the fins 11, where the air is in greatest compression, but may be otherwise located. In Fig. 5. for instance, they are at an angle to the fins, for a purpose hereinafter described, but in this position are still within the compressive effect of the fins on the air due to its tendency to move longitudinally of the blade.

In the trailing edges of the blades are openings or slots 13 forming outlets for the air from the interior of the blades. These outlets should be of greater area than the inlets 12, to avoid the building up of air presblades.

' sure within the compartments formed in the blades.

By this arrangement of ope ings or slots the air rushes into the interior f the blades through the 'slots 12 and thence out through the slots 13 along the trailing edges of the This prevents or tends toprevent the forming of a vacuum or rarefaction of "the air along said edges- In order to take advantage of the impulse reaction of the currents of air thus passing through the blades, I; prefer to place in *each compartment thereof the deflectors 14, which may be of light metal fitted to fill the space between the two faces of the blade and extending diagonally across the compartments,

as shown. The air entering the slot 12 flows toward the inner end of the blade and in so doing strikes the deflector andis-directed-toward the outlet 13. The impulse of the air striking against the deflector results in a thrust thereagainst which is'i'n the direction of the rotation of the blade and to that extent assists in said rotation.

The deflector 14 is also preferably provided with an .inclined rear face 1401, (see Fig. t)

' which is struck by the air as it enters through desired. The cross-sectiona the slot or that portion of the slotopposite the inclined face, and this likewise produces a-thrust on the deflector and blade in a forwarddirection, that'is, in the, direction of rotation. j k

In Fig. 5 the slots 12a follow along above the deflectors 14 instead of at the inner sides of'the vanes or fins,,-whereby substantially all the air entering therethrough impinges upon the inclined face 14a of the deflector lajidi thus produces a forward thrustuponthe From the fore'going the operation will be obvious. The fins 11 prevent or-reducetheslipping of the air longitudinally toward the ends of the blade and the consequent rarethrough the slots by reason of thegreater' compression of the air therealong than if such fins were not used. As heretofore stated, the form, contour and construction of the bl es may be those blades may differ from that shown'in Fig. 4,

and the relative dimensions and proportions of the parts may vary. Likewise, the numform of the berof fins or vanes 11 on the blades may vary,

and their'shape or construction be changed.

These and many other changes may be made without departing from the principle or scope of my invention. particularly as set forth in the appended .claims.

' 1. A propeller for airplanes and the like, having hollow blades, each said blade'having outwardly projecting fins-on its driving face and extending transversely thereof, said blade also having openings in its inner face andin its trailing edge for the passage. of air therethrough.

2. A propeller for airplanes and the like, having hollow blades, each said blade having ontwardly projecting fins on its driving face. and extending transversely thereof, said blade also having openings in its inner face in proximity to the fins and in its trailing edge for the passage of air therethrough.

3.. A propeller for airplanes and the like, having hollow blades, each said blade having outwardly projecting fins on its rear face 1 .cxtendiiigtransversely thereof, said blade "also having openings in its inner face in proximity to the fins and in its trailing edge pt'or the passage of air therethrough, and deflectorswithin the blade in position to be struck by the air entering said face openings. 4;. A propeller for airplanes and the like,

having hollow blade-s, each said blade having outwardly projecting fins on its rear face extending transversely thereof, said blade also having openings in its inner face in proximity to the fins and in its trailing edge for the passage of air therethrough, and deflectors within the blade having rearwardly inclined :faces in position to be struck by the air entering said face openings.

5. A propeller for'airplanes and the like, having hollow blades, each said blade having outwardly projecting fins on its driving face extending transversely thereof, and partitions adjacent the fins for dividing the interior of the blade into compartments, said blade also having openings in its inner face and in its trailing edge for the passage of air through said compartments. 7

6. A propeller for airplanes and the like,. having hollow blades, each said blade having fins projecting outwardly ofits driving face and extending transversely thereof and also extending into the interior of the blade to separate it into compartments, said blade also having openings in its said face in proximity to the fins for the admission of air into said compartments, and said blade also having outlet openings in its trailing edge to per mit the air to escape from said compartment.

7. A propeller for airplanes and the like, having hollow blades, partitions within each blade dividing the interior thereof into compartments, the inner face of the blade having openingsfor the admission of air into a of the blade also having openings to permit said compartments, deflectors in the compartments in position to be struck by the air passing therethrough, and the trailing edge the escape of air from said compartments.

8. A'propeller for airplanes and the like, having hollow blades, each said blade having partitions within the same and dividing the interior of the blade into compartments, thev inner face of the blade'having openings to permit the passage of air into the compartments and the trailing edges of the blade also having openings to permit the air to escape therefrom, and deflectors within the compartments having inclined faces in position to be struck by the air entering said face openings.

9. A propeller for airplanes and the like, having hollow blades, each said blade having fins projecting outwardly of its driving face and extending transversely thereacross, and also extending into the interior of the. blade to separate it into compartments, said blade also having openings in its inner face for the admission ofair into said compartments and outlet-openingsin its trailing edge to permit the escape of air from said compartments, and deflectors within said compartments in position to be struck by the air in its passage therethrough.

10. A propeller for airplanes and the like, having hollow blades, each said blade having fins projecting outwardly of its driving face and extending transversely thereacross, and also extending into the interior of the blade to separate it into compartments, said blade also having openings in its inner'face for the admission of air into said compartments and outlet openings in its trailing edge to permit ,the escape of air from said compartments,

and deflectors within said compartments having inclined faces in position to be struck by the air entering said compartments.

In witness whereof, I have hereunto subscribed my name.

FRANK G. SHERER, 

